Final answer:
Scientists estimate that we add 1 billion people to the Earth's population every 12 years, equivalent to approximately 500 million people per 12 years. The population's growth presents challenges for sustainability and resource management.
Step-by-step explanation:
Scientist estimate that we add 1 billion people to the Earth's population every 12 years. Therefore, the correct answer is D. 500 million, considering that approximately half a billion is added every 12 years due to population growth.
The growth rate of Earth's human population is about 1.4% per year, which would potentially double the population in around 50 years, exceeding 12 billion if the growth continues. At present, the population increase is estimated at about 80 million per year. Historically, it took only 12 years to add the most recent billion to our planet's population, after reaching 7 billion between 1999 and 2011.
Demographers foresee that all population growth by 2050 will occur in developing countries. Despite a slowing growth rate in certain countries, the global population is still rising, with projections for the year 2050 ranging from 9.4 billion to potentially 11 billion.